Petrolatum is a semi-solid mixture of long chain (greater than C=20) hydrocarbons. Petrolatum is a known skin protectant and has been widely used in cosmetic and dermatological applications. Although petrolatum is known to have advantageous protective properties when applied to the skin, its hydrophobic nature had previously made it a poor candidate for formulating active ingredients. It was previously thought that an emulsifier would be necessary to disperse active ingredients throughout petrolatum. It was also thought that the petrolatum was incapable of delivering active ingredients because the active ingredients would be trapped within the petrolatum and therefore would be unable to reach the desired delivery site.
The Applicant has discovered that active ingredients can be formulated in petrolatum. The petrolatum-based compositions described herein contain nanodroplets of active ingredients dispersed in petrolatum. The nanodroplets release the active ingredients to the application site continuously. Additionally, the petrolatum-based compositions described herein are gentle. They do not irritate the skin and are not cytotoxic to mammalian cells. The Applicant has further discovered processes leading to a stable delivery system for a variety of ingredients.